Reference Guide
Low Voltage Motors
ATEX Jargon Buster
ATEX Jargon Buster
ABB’s ATEX jargon buster explains the terminology users are likely to encounter when
purchasing motors for hazardous areas.
ABB’s ATEX Jargon Buster uses hyperlinks for quick navigation. A click on any underlined
word takes you straight to the relevant article.
Quick navigation tool
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A
Approval
Motors are approved for use in hazardous areas by accredited testing laboratories known
as Notified Bodies. To qualify for ATEX approval, manufacturers must show that their
products incorporate measures to prevent the ignition of unavoidable explosive
atmospheres.
See EC Type Examination
ATEX Directives
ATEX is not a standard but an acronym of the French ATmosphères EXplosives, which
stands for Directive 94/9/EC from the Treaty of Rome. This European Directive amends
and adds safety requirements for hazardous areas. The purpose is to enable the sale of
equipment across the European Union, without manufacturers having to satisfy different
requirements for each national market.
If a motor or another piece of equipment is to be used in potentially explosive atmospheres
containing gas or combustible dust, it must comply with the ATEX directive.
ATEX consists of two parts: ATEX 95(*) / ATEX 100a(**), which concentrates on the duties
of the manufacturers; and ATEX 137(*) / ATEX 118(**), which focuses on the end users’
obligations
Compliance with the ATEX directives means reinforced safety aspects – safer design,
more demanding testing procedures, and specific quality assurance measures for the
design as well as the manufacturing process. It requires employers to protect both staff and
local communities from the risk of an explosive atmosphere.
nd
(*) Reference to Article 95 of the Treaty of Amsterdam (2 October 1997)
th
(**) Reference to Article 100a of the Treaty of Rome (25 March 1957)
Compliance with the ATEX directives is mandatory from July 1st 2003.
The ATEX system depends on three key elements: Harmonised technical standards;
production quality assessment of the manufacturing facilities; and notification by the
European Commission to recognize bodies and test laboratories known as Notified Bodies.
2 ATEX JARGON BUSTER
ATEX 95
The product directive 94/9/EC, known as the ATEX 95 Directive, concentrates on the
manufacturer’s duties, giving the safety requirements to be fulfilled by all equipment, both
electrical and non-electrical, installed in hazardous areas within the European Union.
It describes the Essential Health and Safety Requirements (EHSRs) of the products
regarding their design, manufacturing process, testing, documentation and maintainability.
The requirements are divided into three categories: Technical requirements from
harmonised European standards; health and safety aspects; and production quality
requirements.
Voluntary since 1994, the requirements of the Directive are mandatory since 1 July 2003.
The Directive covers any electrical or mechanical product that contains or constitutes a
potential ignition source and which requires a special design or installation procedure to
prevent an explosion. Regulated equipment includes control and communication devices,
monitoring and detection equipment. It also includes safety or control devices installed
outside hazardous areas that have an explosion protection function, such as pressure-relief
panels and fast-acting shutoff valves.
ATEX 100
Article 100 in the treaty of Rome; the same as ATEX 95.
ATEX 118
Article 118 in the treaty of Rome; the same as ATEX 137.
ATEX 137
The “worker protection directive” 1999/92/EC, ATEX 137, describes the “minimum
requirements” for improving the health and safety of workers potentially at risk. It classifies
the environment into zones and outlines which category of equipment that can be used in
each zone.
The Directive focuses on the analysis and description of the risks, the zone definitions, and
the maintenance practices in relation to site safety.
The safety of an installation in a hazardous area is the result of co-operation between the
equipment manufacturer and the end user.
ATEX 137 concentrates on the duties of the end user. Workers should be trained on
hazardous area issues by the employer. Authorization should be given to each employee
working in a hazardous area. Explosion protection measures should be taken and an
explosion protection document (EPD) has to be established. When equipment is repaired,
the end user has the responsibility to select an appropriate repair shop.
The Employers’ obligations in relation to ATEX include assessing the site’s Sources of
Hazard and likely sources of ignition, classification of the area into zones and marking all
points of entry, as well as producing and maintaining documentation. The main obligations
relating to employers are: Preparing an explosion protection document (EPD); classifying
the workplace into Zones where applicable; selecting ATEX 95 products according to Zone;
and identifying, using warning signs, locations where explosive atmospheres may occur.
Essentially, the employer is required to take all reasonable measures to prevent the
formation of an explosive atmosphere in the workplace. Where this is not possible,
ATEX JARGON BUSTER 3
measures must be taken to avoid the ignition of any potentially explosive atmosphere. In
addition, the effects of any explosion must be minimised in such a way that workers are not
put at risk.
Since the ATEX Directives are enforced, the sub-contractors, consultants, and/or service
providers will operate under the responsibility of the end user.
See Third parties
Atmosphere
For ATEX purposes, atmosphere comes in two classifications: “G” for explosive gas and
“D” for combustible dust. A product certified for both gas and dust is marked G-D.
Authorized body
North American terminology. Electrical equipment used in hazardous locations, classified
according to North American rules, must be approved by an authorized body or the
manufacturer.
Bearing currents
Variable Speed Drives can generate high frequency shaft and bearing voltages (see IEC
60034-17), which then can cause bearing currents and damages. Thus in hazardous
environments specially designed Ex-motors and frequency converters must be used. The
protective measures depend for example on voltage, physical size and output power of the
motor. In practice the possible solutions usually are insulated N-end bearing and/or output
filters in the frequency converter and convenient cabling.
Motor intended for variable speed operation will be equipped with a second rating plate,
where the allowed operation conditions are mentioned. The use of Ex-motors in variable
speed drives without the second rating plate is thus prohibited.
For more details see Variable speed drive
C
Canadian Electric Code (CEC)
The general description of hazardous areas and protection types in Canada are presented
in Canadian Electric Code (CEC) published by CSA. More specific requirements can be
found e.g. from several IEEE and UL publications. Electrical equipment used in hazardous
locations, classified according to North American rules, must be approved by an authorized
body or the manufacturer. The equipment for Division 1, Zone 0 or 1 areas must always be
approved by an authorized body e.g. UL, CSA or FM.
4 ATEX JARGON BUSTER
Category
Hazardous area equipment is arranged into categories depending on the level of risk.
The Category defines the level of safety required for the design, testing, installation,
operation, maintenance and repair of the equipment.
The safety requirements are related to the category of the equipment, not to the zone
where it is installed. Consequently, to use equipment from a higher category than required
by the zone will add unnecessary constraints in use and additional costs in inspection,
maintenance and repair, especially in areas affected by combustible dust.
All hazardous area equipment is arranged into one of the following categories:
Category
Zone
Protection in Gas
Protection in Dust
1
0 / 20
Not Applicable
Not Applicable
2
1 / 21
“d”, “e”, “p”
DIP – IP 65
3
2 / 22
“n”, “d”, “e”, “p”
DIP – IP 55 or IP 65
Category 1
Equipment designed for very high level of safety. Requires two independent means of
protection or safe operation with two separate faults. Used where explosive atmospheres
are present continuously or for lengthy periods, typically Zone 0 and Zone 20.
No motors are allowed in theses Zones
Category 2
Equipment designed for a high level of safety. Requires the design to be safe with
frequently occurring disturbances or with one operating fault. Used where explosive
atmospheres are likely to occur, typically Zone 1 and Zone 21.
Category 3
Equipment designed for a normal level of safety. Used where explosive atmospheres are
likely to occur infrequently and to be of short duration, typically Zone 2 and Zone 22.
CEC
See Canadian Electric Code.
CE marking
The CE-Marking affixed to the product is the manufacturer’s statement that
the product complies with the Directives stated in the EC Declaration of
conformity as signed by the manufacturer of the product. The CE mark
shows that the product has been manufactured according to a certain
design and procedure. It works like a passport, allowing a product to be
installed anywhere in the EU. It provides reassurance for buyers both inside and outside
the EU that the motor or machine conforms to the latest standards. For ATEX compliance,
the CE Marking must appear prominently on each item of equipment or each protective
system. In Category 1 or Category 2, it must be followed by the identification number of the
ATEX JARGON BUSTER 5
Notified Body that has approved the product. In Category 3, a statement of compliance
from the manufacturer is acceptable.
CEMEP
A forum for co-operation between European motor manufacturers. Provides a system for
classification of motors based on their energy efficiency. All standard low voltage motors
sold or manufactured in the EU must be classified EFF1, EFF2 or EFF3, where EFF1 is the
highest level of efficiency. Ex-motors are not considered standard motors and are therefore
not subject to the scheme. See http://energyefficiency.jrc.cec.eu.int/eurodeem/index.htm.
CEN - European Committee for Standardization
One of the European Standards Committees. Produces harmonised standards in all fields
except the electrotechnical field and telecommunications, giving the technical means to
achieve the objectives of the Essential Health and Safety Requirements stated in the ATEX
Directive.
CENELEC - European Committee for Electrotechnical Standardization
One of the European Standards Bodies. Produces harmonised standards to cover the
electrotechnical field and gives the technical means to achieve the objectives of the
Essential Health and Safety Requirements stated in ATEX Directives.
Certificates
See Declaration of Conformity.
Circulating current
See Bearing current.
Classification societies
Organisations that verify the technical standard of ships. Requirements on equipment, for
instance motors, may vary from one classification society to the next.
Clearance
Motors designed for hazardous area gas and dust should respect minimum distance in air,
called clearances between two conductive parts (e.g. terminals board) or between rotating
part (e.g. fan and fan cover at least 1mm) to avoid any risks of sparks.
Combustible dust
Combustible dust can be specified either as a dust/air mixture with a specified ignition
temperature, or as a layer of dust of a specified thickness. The ignition temperature for
various types of dust is available from commercially available tables.
Conductive dust
A dust with electrical resistivity equal to or less than 103 ohm.m
6 ATEX JARGON BUSTER
When conductive, the dust is not allowed to enter the motor enclosure, even in zone 22. IP
65 protection shall be requested and motor approved by a Notified Body
Converter Supply
See variable speed drive.
Co-operation
Co-operation is a cornerstone of ATEX 137. The safety of an installation in a hazardous
area is the result of a co-operation of the equipment manufacturer, the installer and the end
user.
Creepage distance
Components used for motors designed for hazardous area gas and dust should respect a
minimum distance along of an insulating material between two conductive parts. This is
known as creepage distance.
CSA
The Canadian Standards Association.
D
D
D on the nameplate indicates that the marking relates to dust. A product certified for both
gas and dust is marked G-D.
Dangerous Substances and Explosive
Atmospheres Regulations
The Dangerous Substances and Explosive Atmospheres Regulations is the UK
implementation of the European ATEX directive. See Local regulations
Declaration of conformity
The EC Declaration of Conformity is the only document that has to be supplied with each
delivery. With this document, the manufacturer takes responsibility for the product’s
compliance with the ATEX directive. It provides information about the EC type examination
certificate, with reference numbers. To ensure that a motor is approved to the appropriate
Directive, users need to check the directive number, which appears in the EC Declaration
of Conformity delivered with the motor. Depending on the zone where the product is used,
the number of the Notified Body can be stamped after the CE mark (mandatory for use in
Zone 1 or Zone 21). This document replaces the previous old certificates.
DIP
See Dust ignition proof
ATEX JARGON BUSTER 7
Directive
A Directive is an EC document issued by the European Community. The aim of a Directive
is to harmonize national provisions to ensure within each country:
-
Safety Aspects
-
Environment
A Directive is published in the Official Journal of European Community (OJEC)
Products are stamped “CE” as a proof of conformity to the Directives, which the EC
Declaration of conformity refers to.
Directive 94/9/EC
See ATEX 95
Directive 1999/92/EC
See ATEX 137
Division system
An old U.S. system, which defines areas according to the so-called Division system (NEC
500). It will soon be replaced by the new NEC 505 standard, similar to the IEC standard.
Dresden agreement
In 1996, IEC and CENELEC reached a co-ordination agreement to develop new standards,
called the 'Dresden agreement'. It means that since September 1996 the same document
is submitted to IEC and CENELEC simultaneously and the standards are published at
same time and are identical. This work stopped between 1998-2000 due to the introduction
of ATEX Directive, pending the publication of harmonised standards. The procedure was
re-introduced in 2001, which means that the IEC standards will be updated over the coming
years in accordance with the EHSRs of ATEX Directive.
DSEAR
See Dangerous Substances and Explosive Atmospheres Regulations and Local
regulations.
Dust
With ATEX, combustible dust is for the first time included in the regulations governing
hazardous atmospheres. Typical applications include handling of grain, coal, sugar, wood
and some chemical substances such as sulphur. Dust ignition proof motors have been
designed to provide safe motive power in these areas.
Dust cloud
The risk of explosion in a hazardous area with combustible dust is either caused by a cloud
of dust or a layer of dust.
The ignition temperature for a cloud of dust must be at least 50% above the motor’s
marking temperature; or, put differently, the marking temperature must not exceed two8 ATEX JARGON BUSTER
thirds of the ignition temperature of the dust. For instance, if the ignition temperature of the
dust is 210°C, the motor’s marking temperature must be lower than 140°C.
The ignition temperature of a 5mm layer of dust must be 75°C above the marking
temperature of the motor. For instance, if the ignition temperature is 200°C, the marking
temperature must be 125°C or lower. It is the responsibility of the user to stage
maintenance periods so that the dust layer does not build up above 5mm. The ignition
temperatures for various types of dust are available from commercially available reference
tables.
Dust ignition proof
Dust Ignition Proof (DIP) motors are used in atmospheres where combustible dust
surrounds the motor, or where dust settles under its own weight on the motor. Typical
applications include handling of cereal, animal feed, paper, wood, chemicals, plastics and
coal.
On a DIP motor, the cooling fan is made of metal or other anti-static material, to avoid static
electricity. The terminal board has increased clearances to guarantee higher security. The
temperature marked on the motor will correspond to the running performance during the
worst conditions allowed for the model. Motors for Zone 21 are protected to IP 65 as
minimum.
For Zone 22, protection to IP 55 will be used if the dust is not conductive, but IP 65 will be
necessary when the dust is conductive.
This degree of protection will prevent any explosion of combustible dust from being
transmitted, because the motor itself is dust ignition proof. This means no potentially
explosive atmosphere can penetrate inside the motor. The ingress of dust into the motor is
prevented by the IP protection and the temperature marked on the motor corresponds to
the temperature class for which the motor is certified in respect to standards.
The use of IP 65 protection requires regular inspection and maintenance.
Dust ignition temperature
The ignition temperature for various types of dust can be obtained from commercially
available tables. The maximum temperature of the motor is relative to the ignition
temperature of the prevailing dust. See Temperature class.
E
EC Declaration of Conformity:
See Declaration of Conformity
EC Type Examination
An EC Type Examination certificate is a document issued by an Ex NB accredited by the
EU according to ATEX Directive 94/9/EC (ATEX 95) which allow them to issue this
Certificate for Category 1 and Category 2 .
The Ex NB’s are not allowed to issue an "EC Type Examination Certificate" according to
94/9/EC for category 3, only Statements of Compliance (or type examination certificate) is
allowed.
ATEX JARGON BUSTER 9
EEx d
See Flameproof
EEx de
See Flameproof
EEx e
See Increased safety
EEx nA
See Non Sparking
EEx p
See Pressurized Enclosure
EEx pe
See Pressurized Enclosure
EFF1
The highest level of motor efficiency in the European classification system, established
through cooperation between CEMEP and the European Commission.
Efficiency classification
See CEMEP and EPCA.
EHSR’s
See Essential Health and Safety Requirements.
10 ATEX JARGON BUSTER
Electrical Insulation Resistance
The electrical insulation resistance of fans, fan cover and ventilation screen should not
exceed 1 GigaOhm if peripheral speed of fan is equal or more than 50m/s for gas
environment. For Dust Ignition Proof motors, it should not exceed 1 Gohm whatever the
peripheral speed of the fan.
For all hazardous area the fan, fan cover or ventilation screen should not contain more than
6% of magnesium by mass. All surfaces which can charge electrically, should be earthed
or connected with equipment bond.
Employers’ obligations
See ATEX 137.
EN - European Norm
See European standards
End user
The duties of the end user company are outlined by the ATEX 137 directive.
EPAct
See EPCA
EPCA
The American Energy Policy and Conservation Act, often referred to as EPAct or EPCA,
requires electric motors in the range 0.75 to 132 kW (1-200 hp), manufactured in or
imported to the United States, to meet specific energy efficiency standards. The regulations
also apply in Canada, where the legislation is referred to as the “Energy Efficiency
Regulations” and “Canada’s Energy Efficiency Act”. For further information about the
efficiency levels required, contact ABB.
EPD
See explosion protection document.
Equipment category
See Category.
Essential Health and Safety Requirements (EHSR)
The ATEX 95 Directive defines the “essential health and safety requirements” (EHSRs) of
equipment for each Category. Different types of protection can be used to respect the
EHSRs of ATEX Directive according to the Zones where the equipment is installed. The
goal is to prevent the creation of a source that can create an explosion. The ATEX 137
Directive directly concerns the minimum requirements that are to be respected in different
ATEX JARGON BUSTER 11
working places(Zone area). The safety of an installation in a hazardous area is the result of
a co-operation of the equipment manufacturer, the installer and the end user.
See also New approach directives.
European standards
A unified set of standards has been developed in the European Union. The goal is to have
standards, which are accepted, and adopted, by all European countries. These European
standards are commonly referred to as the European Norm (EN). The European standards
Committee provide the leadership for the development of these standards.
The European standards for ATEX are issued by the European Standards Committee:
CEN - European Committee for Standardization; and CENELEC - European Committee for
Electrotechnical Standardization. These bodies produce harmonised standards to cover the
electrical and mechanical fields and give the technical means to achieve the objectives of
EHSRs stated in the ATEX Directives. In 1996, IEC and CENELEC made a co-ordination
agreement to develop new standards called the 'Dresden agreement'. It means that since
September 1996 the same document is submitted to IEC and CENELEC simultaneously
and the standards are published at same time and are identical.
European Standards Committees
National standards are generally drawn up by private national standards organisations.
These are in charge of standardization in their respective country. These bodies meet
within three European organizations, which are also private:
CEN, the European Committee for Standardization, working in all fields except the
electrotechnical field and telecommunications; CENELEC, the European Committee for
Electrotechnical Standardization, and ETSI, the European Telecommunications Standards
Institute.
The prime task of these organizations is the establishment and promotion of European
standards, recognized by all member countries. This leads to the production of genuine
European standards, which help to abolish technical barriers ensuring that, when a
standard is used, the same standards are applied in all the member countries.
Ex d
See Flameproof
Ex de
See Flameproof
Ex e
See Increased safety
Ex mark
The Ex mark is the European Commission mark for
products approved for hazardous areas.
12 ATEX JARGON BUSTER
Ex-motors
See hazardous area motors.
Ex nA
See Non-sparking
Ex Notified Body Group (ExNBG)
Hazardous area products are approved by the Notified Bodies, known collectively as the Ex
Notified Body Group (ExNBG). These are test laboratories approved, or ’notified’, by the
European Commission. Under the old directives, these were referred to as 'Heads of Test
Laboratories' (HOTL: Head Of Testing Laboratories).
Ex p
See Pressurized Enclosure
Ex pe
See Pressurized Enclosure
Examination certificate
The Notified Body examines and tests the product to confirm it meets the standard and
issues an EC-type examination certificate to the manufacturer, entitling him to display the
CE mark on the product as proof of compliance.
See EC Type examination certificate.
Ex NB
See Notified Bodies.
Explosion protection document
The employer must carry out an assessment of risks arising specifically from explosive
atmospheres and produce an Explosion Protection Document that demonstrates that
explosion risks have been assessed. This should be at most 3 – 4 pages in length and
contain the references to the whereabouts and mapping interpretation of the minimum
requirements to the existing current safety management system documentation.
Explosive atmosphere
An explosive atmosphere is a mixture of air, under atmospheric conditions, of flammable
substances in the form of gas, vapour, mist, dust, or fibres in which, after ignition,
combustion spreads throughout the unconsumed mixture
Potentially explosive atmospheres are found in many areas of industry, from mines and the
chemical, oil and gas, and pharmaceuticals industries, to plants handling cereal, animal
feed, paper, wood and coal. All these have the potential to produce gas, dust or fumes
which can be ignited by a spark or flame.
ATEX JARGON BUSTER 13
The classification of the potentially explosive atmosphere depends on the frequency with
which potentially explosive atmosphere may exist and the capability of the gas or dust to
create an explosion.
Explosive gas and combustible dust is classified according to its likelihood to be ignited,
according to its characteristics: Minimum ignition energy; Minimum ignition temperature;
Auto-ignition temperature; and Layer ignition temperature
F
Flamepath
A route for exploding gas to escape from the machine by, whilst cooling off. This is
achieved by making the gas take a long route along extra long spigots etc. “Length of
flamepath” refers to the shortest through a flameproof joint from the inside to the outside of
a flameproof enclosure.
Flameproof enclosure, type “d”
Flameproof is the common name for enclosure type “d”, explosion proof enclosure. The
designation under ATEX for this type of motor is EEx d. The corresponding designation
according to IEC is Ex d.
The enclosure of this motor type will prevent an internal explosion, or flame, from being
transmitted to the explosive atmosphere surrounding the machine, hence the name
flameproof. The enclosure will withstand any pressure levels caused by such an internal
explosion. The design includes a flamepath. There may be no dangerous hot surface or
sparks on the outside of the enclosure at rated operation.
There is also another variant designated EEx de or Ex de. This is a a flameproof motor with
the terminal box of an increased safety motor, combining the superior safety of a “d”
protection with the less stringent electrical connection requirements of an EEx e or Ex e
motor.
Flameproof motors are designed as Category 2 equipment for use in zone 1, but they can
also be used in zone 2.
Flameproof bushing
An insulating device carrying one or more conductors, through internal or external walls of
a flameproof enclosure without affecting the flameproof properties of the enclosure or its
compartments.
Flameproof joint
The place where corresponding surfaces of the different parts of a flameproof enclosure
come together and prevent the transmission of an internal explosion to the explosive gas
atmosphere surrounding the enclosure. See also flamepath.
FM
Stands for Factory Mutual Research, a US based, non-profit scientific research and testing
organisation.
14 ATEX JARGON BUSTER
Frequency converter
See variable speed drive.
G
G-D
A product certified for both gas and dust is marked G-D. If a motor is to be installed in an
environment that contains gas and dust, the motor needs to fulfil the requirements for both.
For instance, an EEx d motor in temperature class T4 and modified for use as a DIP motor,
could be installed in both atmospheres.
Gap of flameproof joint
The distance between the corresponding surfaces of a flameproof joint when the motor has
been assembled.
Global ATEX system
The term 'Global ATEX system' refers to the three key elements necessary for ATEX
compliance: Harmonised standards, covering the EHSRs of ATEX Directive; audits at the
manufacturing facility responsible for delivering the Ex-equipment, conducted by an expert
for quality Ex-system approved by European Commission; and a notification by the
European Commission to recognize bodies and test laboratories known as the 'Ex Notified
Body Group' (ExNBG).
Group
Under the ATEX Directive, equipment is designated by the type of potentially explosive
atmosphere in which the equipment may be used – Group 1 for underground mines and
Group 2 for surface industries.
H
Harmonised Standard
Harmonised Standards are listed in the Official Journal of the European Communities to
offer guidance to conformity with a particular Directive. See European Standards
Committee and New approach directives.
Hazardous area
Explosive atmosphere is referred to as "Hazardous area" in IEC countries and "HAZLOC"
in North America.
ATEX JARGON BUSTER 15
Hazardous Area Motors
Motors designed to meet high safety requirements to prevent any risk of ignition of
explosive atmospheres, even under fault or in recognised overload conditions. Testing and
certification by Notified Bodies ensures that the requirements are met.
The use of hazardous area motors is mandatory in explosive atmospheres, however they
are also frequently used in severe environments, corrosive atmospheres or anywhere else
where reinforced protection is required.
HAZLOC
Explosive atmosphere is referred to as "Hazardous area" in IEC countries and "HAZLOC"
in North America.
Heads of testing laboratories (HOTL)
See Ex Notified Body Group.
Health and Safety at Work Act
Any incident in relation to hazardous areas, which involves injury or damage, would fall
within the scope of legislation such as The Health and Safety at Work Act. This provides for
much higher penalties than incidents under the more familiar Machinery Safety
Regulations.
Health and safety requirements
See Essential Health and Safety Requirements (EHSRs).
Highly Flammable Liquids & Petroleum Gases
Regulations 1972
Part of older UK legislation, replaced by the new 17 part regulations under DSEAR. This
will deal with explosions and fires that are caused by dangerous substances that generate
explosive atmospheres whether they are gases, vapours or dusts.
I
IEC
Stands for International Electrotechnical Commission. International standards for all
electrical, electronic and related technology areas are issued by IEC. It is made up of more
than 60 participating countries, with the major goals being to make the global market work
more efficiently; to improve efficiency in industrial processes; to improve health and safety;
and to protect the environment. An IEC Ex-scheme is in progress to harmonise the
international requirements for hazardous applications.
IEC standards have no legal standing in any country, however they do tend to influence
local regulations.
16 ATEX JARGON BUSTER
IEEE
The IEEE (pronounced Eye-triple-E) is a non-profit, technical professional association of
more than 377,000 individual members in 150 countries. The full name is the Institute of
Electrical and Electronics Engineers, Inc. Based in the United States; it is involved in
technical publishing, conferences and consensus-based standards activities.
Ignition
The relevant parameters to characterise the potentially explosive atmosphere are:
Frequency with which potentially explosive atmosphere may exist; Minimum ignition
energy; minimum ignition temperature; auto-ignition temperature; and layer ignition
temperature
Ignition temperature of an explosive substance
The lowest temperature of a hot surface at which ignition occurs of a flammable
substance.
Increased safety
Under ATEX, the type designation for this type of motor is EEx e. The corresponding
designation according to IEC is Ex e.
Increased safety motors prevent sparks, arcs or hot spots during service, including starting,
by a number of constructional or dimensional provisions, and by the use of special
protection devices, designed to trip within a specified time in case of stall position.
The maximum stall time “tE” allowed for the motor is stamped on name plate, this tE time
respect a minimum value depending of ratio IS/IN (given by the Standards)
To reduce the temperature rise, this type of motor typically has a special winding that
effectively de-rates the motor in its increased safety design. In practise it means the
customer will have to select a bigger motor compared to a flameproof motor for the same
application.
Increased safety motors are designed as Category 2 equipment for Zone 1, but can also be
used in Zone 2.
Insulated Bearings
See bearing currents.
International standards
Equipment for explosive atmosphere is designed, installed, operated and maintained
according to international standards and local regulations dedicated to this area. See IEC:
International Electrotechnical Commission; EN: European Norm; and NEC: National
Electrical Code for North America
ATEX JARGON BUSTER 17
J
July 2003
1st of July 2003 is the implementation date for ATEX, marking the end of the transition
period. This means that from this date, any Ex-equipment put on the market in a hazardous
area in Europe must be ATEX certified. This deadline includes any spare parts for
equipment, protective systems, components or devices that falls under the ATEX Directive.
L
Layer ignition temperature
The risk of explosion in a hazardous area with combustible dust is either caused by a layer
of dust or a cloud of dust.
The ignition temperature of a 5mm layer of dust must be 75°C above the marking
temperature of the motor. For instance, if the ignition temperature is 200°C, the marking
temperature must be 125°C or lower. It is the responsibility of the user to stage
maintenance periods so that the dust layer does not build up above 5mm. The ignition
temperatures for various types of dust are available from commercially available reference
tables.
The ignition temperature for a cloud of dust must be at least 50% above the motor’s
marking temperature; or, put differently, the marking temperature must not exceed twothirds of the ignition temperature of the dust. For instance, if the ignition temperature of the
dust is 210°C, the motor’s marking temperature must be lower than 140°C.
Limiting temperature
Relevant to increased safety electrical apparatus. The maximum permissible temperature
of apparatus of parts of apparatus equal to the lower of the two temperatures determined
by:
a) the danger of ignition of the explosive gas atmosphere
b) the thermal stability of the materials used.
Loadability curve
The loadability curve gives the maximum torque at various speeds in variable speed drive
operation.
Local regulations
See national regulations.
M
Maintenance
Inspection and maintenance operations under ATEX are described in EN 60079-17 for gas
and in EN 50281-1-2 for dust. It is the responsability of the end user to ensure the safety of
these operations, especially when sub-contracted.
18 ATEX JARGON BUSTER
MEPS
Australian Standards MEPS (Minimum Energy Performance Standards) for High Efficiency
(AS/NZ 1359.5:2000).
Marking
Products that meet the requirements of the ATEX Directive are marked by the
manufacturer with the CE mark and the Ex mark. The following information is also required:
name and address of manufacturer; designation of series or type; serial number, if any; and
the year of manufacture. The Ex symbol should be followed by the equipment group and
category. For equipment Group II the letters G and/or D for type of atmosphere (gases,
vapours, mists and dusts); the symbol for the temperature class or the maximum surface
temperature, or both; the Ex symbol, followed by the symbol for the type(s) of protection
used and the identity of gas or gas group covered; the identity of the Notified Body involved
at the certification stage and the certificate number; and any additional marking required for
the type of protection concerned.
A typical hazardous motor description could look like this:
Maximum permitted gap
The highest value of gap, defined according to the electrical apparatus group, the volume
of the flameproof enclosure and the length of the flameproof joint.
Maximum surface temperature
The highest temperature attained in service under the most adverse operating conditions
within the rating of the electrical apparatus by any part or any surface of the apparatus that
could produce an ignition of the surrounding explosive atmosphere
Minimum Requirements
The ”Minimum requirements” are listed in part A of annex II of the Worker Protection
Directive 1999/92/EC (ATEX 137). These outline what the end user needs to do to fulfill
health and safety obligations.
The minimum requirements cover the training and competences of the workers, the writing
of all instructions for the operations maintenance, inspection, the description of the
Explosion Protection Measures, the verification procedures before start up, the role of the
safety manager, the traceability of all operations in relation with the the safety including the
audit, qualification and control of the suppliers, service providers and sub-contractors.
ATEX JARGON BUSTER 19
All these points must be documented and updated in the Explosion Protection Document
These ”Minimum Requirements” apply to all ”Work equipment” from July 1st 2003 even if it
was installed before that date and is not ATEX certified.
Motor design
Hazardous area motor designs must use the minimum values for clearances and creepage
distances outlined in the latest edition of standards.
Insulating material with the highest class of resistance for tracking is used. In the case of IP
54 or IP55 protection, the clearance between fan and fan cover must be at least 1% of the
maximum diameter of fan, with a minimum value of 1 mm and a maximum of 5 mm. The
insulation resistance of fans, fan cover and ventilation screen should not exceed 1 gigaohm
if peripheral speed of fan is equal or more than 50 m/s for gas environment. This always
applies for Dust environment, even if peripheral speed is below 50m/s. The fan, fan cover
or ventilation screen should not contain mass of more than 6% of magnesium.
All surfaces, which can charge electrically, should be earthed or connected with
equipotential bond. Temperature of the relevant surface for determining the temperature
class (external or internal surface) is determined by measuring the maximum temperature
rise in worst condition whatever the network supply voltage, between 95% and 105% of UN
during rated operation, with an additional margin of 5° below the temperature class.
Motor grouping
See Group.
N
National Electrical Code (NEC)
The general description of hazardous areas and protection types in the United States are
presented in the National Electric Code (NEC) published by the National Fire Protection
Association (NFPA). More specific requirements can be found in publications from e.g.
IEEE and UL. Electrical equipment used in hazardous locations, classified according to
North American rules, must be approved by an authorised body or the manufacturer. The
equipment for Division 1, must always be approved by an authorized body e.g. UL, CSA or
FM.
National Fire Protection Association (NFPA)
US based, non-profit organisation aiming to reduce the burden of fire and other hazards
and advocating scientifically-based consensus codes and standards, research, training and
education. Its membership totals more than 75,000 individuals from around the world and
more than 80 national trade and professional organizations
National regulations
Equipment for explosive atmospheres is designed, installed, operated and maintained
according to international standards and local regulations dedicated to this area.
Each country has its own regulations, which may differ. National requirements might be
needed for final approval of installations e.g. in Russia, Brazil, Australia or Japan but
generally relate to one of the main international standards.
20 ATEX JARGON BUSTER
NEC
See National Electrical Code
NEC 500
Used in the U.S., this is the actual standard defining the hazardous area according to the
Division system.
NEC 505
This American standard defines the relationship between the Divisions as described in
NEC 500 and the Zones used in the IEC system. The law enforcing this standard has never
been published in the United States so it can be used only for items exported from the
United States.
NEMA
National Electrical Manufacturers Association, the leading US trade association
representing the interests of electrical industry manufacturers. Sets standards relating to
electric motors.
New approach directives
In the past, EU Directives and Standards contained strict lists of requirements that needed
to be fulfilled.
The New Approach Directives have introduced a new logic, where the goal of safety is
defined through Essential Health and Safety Requirements (EHSR) or Minimum
Requirements. Manufacturers and end users then have the freedom to find the best means
to meet the stated goal.
This explains why the in the relevant standards many requirements are requested as
“should” instead of “shall”, or appear as a note.
The purpose is to help engineers find cost-effective and convenient solutions without
compromising safety.
Non-explosive atmosphere
An atmosphere with no explosive elements. All types of standard products can be used.
Hazardous area motors are however also frequently used in non-explosive atmospheres,
for instance in severe environments, corrosive atmospheres or anywhere else where
reinforced protection is required.
Non-sparking
The designation for this type of motor under ATEX is EEx nA. The corresponding
designation according to IEC is Ex n A. The letter “A” stands for non-sparking equipment
according to EN50021.
With this type of protection, measures are applied to give security against the possibility of
excessive temperatures and of the occurrence of arcs and sparks inside and on external
parts of electrical apparatus which does not produce arcs or sparks in normal service.
The EHRS (Essential Health and Safety Requirements) introduced by ATEX now make this
design safer against the risk of sparks during starting.
ATEX JARGON BUSTER 21
Non-sparking motors are for use in zone 2 only, i.e. for areas where explosive atmospheres
occurs occasionally, but not during normal duty. EEx nA motors are not flameproof, and
have no flamepath. The equipment is classified as Category 3.
Norsok
Recommendations used by the Norwegian offshore industry
North American regulations
The general standards for the electric motors according to North American regulations are:
NEMA Motors and Generator (MG-1) in the U.S.; and C22.2 No. 100-95 in Canada. The
general description of hazardous areas and protection types are presented in the National
Electric Code (NEC) published by National Fire Protection Association (NFPA) and in
Canadian Electric Code (CEC) published by CSA. More specific requirements can be found
e.g. from several IEEE and UL publications. An authorized body or the manufacturer must
approve electrical equipment used in hazardous locations, classified according to North
American regulations. An authorized body e.g. UL, CSA or FM must always approve the
equipment for Division 1, Zone 0 or 1 areas.
Notified Bodies
Approval of design and manufacture is issued by Notified Bodies, independent testing
laboratories recognised to perform tests, audit quality systems and issue reports and EC
Type Examination or certificates of conformity.
In hazardous areas, the manufacturer must use an European Notified Body for testing and
certification of the products according to the category requirements, usually a company that
specialises in testing industrial equipment.
The notified body examines and tests the product to confirm it meets the standard and
issues an EC-type examination certificate to the manufacturer, entitling him to display the
CE mark on the product as proof of compliance. A new feature of the ATEX Directive is that
the manufacturer now also needs a quality system in place that must be checked by the
Notified Body.
To ensure that a motor is approved to the appropriate Directive, users need only to check
the directive number, which appears in the EC Declaration of Conformity delivered with the
motor. Depending on the zone where the product is used, the number of the notified body
can be stamped after the CE mark (mandatory for equipment category 2).
See also http://europa.eu.int/comm/enterprise/atex/nb/nblist.htm.
P
Pressurised enclosure
The designation under ATEX for this type of protection is EEx p. The corresponding
designation according to IEC is Ex px or Ex py or Ex pz.
High voltage motors are available with a pressurised enclosure that can be purged and
filled with an inert gas to prevent an explosion.
They meet the most stringent safety requirements for hazardous areas in the chemical and
mineral oil industries. These motors are typically used instead of EEx nA in high voltage
applications, 11kv or more, where a higher level of protection is desired.
22 ATEX JARGON BUSTER
The decision weather to use either EEx d or EEx p in a high voltage application is looked at
on a case-by-case basis. It is often possible to offer a smaller frame size for the EEx p
motor, but this is then offset by the need to provide the purging gas and the associated
pipe-work.
There is also another variant designated EEx pe (alternatively Ex pxe or Ex pye or Ex pze).
No dangerous hot surface or sparks is permitted on the outside of the enclosure. The
temperature of all parts inside the enclosure must be under the T-class limit under normal
operating conditions.
Pressurised motors are designed as Category 2 equipment for Zone 1, but they can be
used in Zone 2.
Product Directive 94/9/EC
See ATEX 95 .
Protection types
Motors are available in the following protection types: Flameproof; Increased safety; Nonsparking; Pressurised; and Dust ignition proof.
Production quality assessment
A new feature of the ATEX Directive (ATEX 95) is that the manufacturer now also needs a
quality system in place that must be checked by the Notified Body. The production quality
assessment of the manufacturing facility responsible for delivering Ex equipment is one of
the three key elements in the ATEX system. The other two are the harmonised standards
for equipment and the notification by the European Commission to recognize bodies and
test laboratories as Notified Bodies.
This production quality assessment applies to the manufacturer, to the suppliers and
service providers of the manufacturer. It has a 3 years validity and requests a yearly audit .
Q
Quality assurance
Specific quality assurance is required for the design and the manufacturing process relating
to hazardous area motors. See production quality assessment.
R
Recognised test organisations
See notified bodies.
Repair
Repair operations must respect strict requirements as described in IEC 60079-19 for gas
and EN 50281-1-1 for dust, the end user has the responsibility to select an appropriate
repair shop. See ATEX 137.
ATEX JARGON BUSTER 23
S
Standards EN / IEC
EN Standards are issued by the European Comittee of Standardization, see CEN.
IEC Standards are issued by the International Electrotechnical Comission, see IEC.
There is a clear trend for the requirements harmonisation between the CEN and the IEC.
See Appendix 1 for the list of the ATEX relevant EN and IEC Standards.
Second rating plate
Hazardous area motors for variable speed drive applications can be fitted with a second
rating plate, outlining its limitations in this configuration. See Variable Speed Drive.
Self-certification
For electrical equipment classified as category 3 according to Product Directive(ATEX 95)
where the requirements are less stringent, the ATEX Directive allows manufacturers to selfcertify products, although third-party certification is often preferred.
Shell Dep
Shell specifications also used by other companies of oil and gas sector.
Sources of Hazard
The Employers’ obligations in relation to ATEX include assessing the site’s Sources of
Hazard and likelihood of sources of ignition, classification of the area into zones and
marking all points of entry, as well as producing and maintaining documentation. See ATEX
137.
Statements of Compliance
A Statement of Compliance (sometimes called “type examination certificate”) may be
issued by testing laboratories, recognized by official organizations in Europe, as third party
and independent testing laboratories for category 3.
The content is different from an “EC Type Examination Certificate” issued for category 1
or 2.
24 ATEX JARGON BUSTER
T
Temperature class
Temperature
class, gas
Temperature °C
T1
450
T2
300
T3
200
T4
135
T5
100
T6
85
An Ex product should be marked with the corresponding temperature class. The
temperature class corresponds to the maximum surface temperature of the product.
According to the type of protection used, the temperature corresponds either to maximum
temperature of external surface or to the maximum temperature inside. In every case, the
temperature should be below the minimum ignition temperature of the explosive
atmosphere where the motor is installed. It is the responsibility of the user to observe an
appropriate margin between the minimum ignition temperature and the temperature
marked on the motor.
For dust ignition proof motors, the marking temperature corresponds to the temperature
class of the motor. This temperature will correspond to the maximum temperature of the
external surface of the motor with a safety margin of 5º K.
Temperature class, dust
Substance
Wheat
Barley
Charcoal
Corn
Sugar
Sulphur
PVC
Ignition
temperature
for cloud of
dust
420
450
500…600
400
350
240
530
Ignition
temperature
for layer of
dust = 5mm
200
205
180
250
220
250
340
Max allow.
Surf. Temp.
(layer <= 5mm)
125
130
105
175
145
160
265
Temp class,
dust
T125
T130
T105
T175
T145
T160
T265
T5
T5
T4
T4
T4
T3
Corresponding T5
temp class,
gas
ATEX JARGON BUSTER 25
Temperature rise
Variable speed drives creates extra losses inside the motor, because of the non-sinusoidal
wave they produce compared to the 50 or 60 Hz industrial network. This increases the
temperature rise compared to the temperature rise at same torque with network supply. For
this reason, hazardous area motors intended for variable speed drive applications must be
fitted with a second rating plate.
Test organisation
See Notified bodies.
Testing laboratories
See Notified bodies.
tE-time
This refers to the maximum stall time of the motor. The maximum stall time “tE “ allowed for
the motor should be stamped on rating plate. The tE time should respect a minimum value
depending of ratio Is/IN (given by the Standards). Only applicable for EEx e.
Third Parties
As there are only two ATEX Directives, the Product Directive (ATEX 95) and the Workers
Directive (ATEX 137), the areas of responsibility are split between the manufacturers and
the end-users without the involvement of anyone else.
Any third parties involved operate under the responsibility or either the manufacturer or the
end user.
Type of protection
The special design applied to motor to prevent ignition of a surrounding explosive
atmosphere.
Transition period
The ATEX Directive was adopted in 1994. Since 1st of July 2003 the ATEX Directives are
mandatory and the transition period is over.
U
UL
Underwriters Laboratories Inc. (UL) is an independent, not-for-profit product safety testing
and certification organization, based in the United States.
26 ATEX JARGON BUSTER
V
Variable speed drive
Because of the non-sinusoidal wave produced by the variable speed drive compared to the
industrial network, extra losses are created inside the motor. These losses increase the
temperature rise compared to the temperature rise at same torque with network supply.
Machines in variable speed operation are also susceptible to bearing currents, which may
cause sparking.
Motors for use with a variable speed drive must therefore meet specific “Minimum
Requirements”. In the rating plate(s) the following values must be shown:
-
speed range
-
power range
-
voltage & current range
-
type of torque
-
converter type and required minimum switching frequency
For these applications, the dimensioning and installation are critical. The user should follow
the manufacturer’s instructions carefully.
The new standards allowing the use of Ex-motors with variable speed drive supply consider
the motor and the converter as a 'unit' and require them to be tested together for
certification. In case of flameproof motors, the tests do not need to be carried out when
there is a direct temperature control using embedded temperature sensors.
VIK
Recommendations used mostly only in the German chemical, gas and oil industry.
VSD
See variable speed drive.
W
Worker Protection Directive
See ATEX 137.
Z
Zone
Hazardous places/environment are classified in terms of zones on the basis of the
frequency and duration of the occurrence of an explosive atmosphere
ATEX 137 Directive divides hazardous environment into zones and states which category
of equipment that can be used in each zone.
ATEX JARGON BUSTER 27
Atmospheres are classified into zones. Zones 0, 1 and 2 refer to gas, while Zones 20, 21
and 22 refer to dust.
Zone 0
Explosive atmosphere with gas or vapour present continuously, for long periods or
frequently due to malfunctions, typically more than 1000 hours per year. No motors are
allowed in Zone 0.
Zone 1
Explosive atmosphere containing gas or vapour is likely to occur due to expected
malfunctions, typically between 10 and 1000 hours per year. Flameproof or increased
safety or Pressurized motors can be used in Zone 1.
Zone 2
Explosive atmosphere containing gas or vapour is unlikely to occur, or, if it does, is likely to
only be of short duration and not during normal duty, typically less than 10 hours per year.
Increased safety motors or non-sparking motors are used in Zone 2.
Zone 20
Permanent presence of combustible dust. No motors are allowed in Zone 20.
Zone 21
Incidental presence of combustible dust during normal duty. Only dust ignition proof motors
approved and certified by a Notified Body can be installed.
Zone 22
Presence of combustible dust only by accident, but not during normal duty. Dust ignition
proof motors approved by a Notified Body or by the manufacturer can be used here if nonconductive dust.
Zoning
The division of a hazardous area into zones depending on the frequency with which
explosive atmosphere occurs. The overall aim is to ensure that the employees and the
public are protected from fires and explosion.
It involves identifying and assessing the fire and explosion risks of dangerous substances
within the operating plant. Properties of materials are to be agreed and documented. Safety
measures to eliminate or reduce the risks of these substances are put in place.
Once no further improvements can be made to the operation, the plant can be put forward
for risk assessment and area classification.
28 ATEX JARGON BUSTER
Appendix 1
List of the EN / IEC Standards
Standards for classification in Hazardous Areas
EN Standards
EN 1127-1 (1997)
Explosive atmospheres - Explosion and protection, Part 1: Basic concepts and methodology
EN 50281-3 (Sept.
2002)
Equipment for use in the presence of combustible dusts, Part 3: Classification of areas where
combustible dusts are or may be present
IEC Standards
IEC 60079-10 (June
2002)
Electrical apparatus for explosive gas atmosphere, Part 10: Classification of hazardous areas
IEC 61241-3 (June 2002) Electrical apparatus for use in the presence of combustible dust, Part 3: Classification of areas where
combustible dusts are or may be present
Standards for Installation, Inspection and Repair
EN Standards
EN 60079-14 (Aug. 1997)
Electrical appartus for explosive gas Atmospheres Part 14 Electrical Installations in hazardous
areas
EN 60079-17 (Aug. 1997)
Electrical appartus for explosive gas Atmospheres Part 17 Inspection and Maintenance of Electrical
Installations in hazardous areas
EN 50281-1-2 (Sept. 1998) +
EN 50281-1-2/A1 (2002)
Electrical appartus for use in the presence of combustible dust Part 1-2: Electrical appartus
protected by enclosures- Selection, installation and maintenance
IEC Standards
IEC 60079-14 (Oct. 2002
Electrical appartus for explosive gas Atmospheres Part 14 Electrical Installations in hazardous
areas
IEC 60079-17 (July 2002)
Electrical apparatus for explosive gas Atmospheres Part 17 Inspection and Maintenance of
Electrical Installations in hazardous areas
IEC 60079-19 (Sept. 1993)
Electrical apparatus for explosive gas Atmospheres Part 19 Repair and overhaul for apparatus
used in Explosive Atmospheres
IEC 61241-1-2 (June 1999)
Electrical apparatus for use in the presence of combustible dust Part 1-2 Electrical apparatus
protected by enclosure and surface temperature temperature limitation- Selection, installation and
maintenance
ATEX JARGON BUSTER 29
Standards for equipments
EN Standards
EN 50014 (June 1997) +
EN 50014/A1(Feb. 1999) +
EN 50014/A2(Feb. 1999)
Electrical apparatus for potentially atmospheres: General requirements
EN 50016 (July 2002)
Electrical apparatus for potentially atmospheres: Pressurized apparatus ‘p’
EN 50018 (Nov. 2000) +
EN 50018/A1 (2002)
Electrical apparatus for potentially atmospheres: Flameproof enclosure ‘d’
EN 50019 (July 2000) +
Corrigendum 4.2003
Electrical apparatus for potentially atmospheres: Increased safety ‘e ‘
EN 50021 (April 1999)
Electrical apparatus for potentially atmospheres: Type of protection ‘n’
EN 50281-1-1 (Sept. 1998) + Electrical apparatus for use in the presence of combustible dust Part 1-1: Electrical apparatus
50281-1-1/A1(2002)
protected by enclosures - Construction and testing
IEC Standards
IEC 60079 – 0 (June 2000)
Electrical apparatus for explosive gas atmospheres Part 0: General requirements
IEC 60079 – 1 (Feb. 2001)
Electrical apparatus for explosive gas atmospheres Part 1: Flameproof enclosures “d”
IEC 60079 – 2 (Feb. 2001)
Electrical apparatus for explosive gas atmospheres Part 2: Pressurized enclosures “p”
IEC 60079 – 7 (Nov. 2001)
Electrical apparatus for explosive gas atmospheres Part 7: Increased safety “e”
IEC 60079-15 (Feb. 2001)
Electrical apparatus for explosive gas atmospheres
IEC 61241-1-1 (June 1999)
Electrical apparatus for use in the presence of combustible dust Part 1-1: Electrical apparatus
protected by enclosure and surface temperature limitation- specification for apparatus
Others
AS 2380.9 (1991)
30 ATEX JARGON BUSTER
Electrical equipment for explosive atmospheres – Explosion-protection techniques Part 9: Type of
protection n- Non-sparking
www.abb.us/lowvoltage
BR413 6/11 TCP
Printed in the USA
LVM REF ATEX EN 04-2010
ABB Inc.
Baldor
Electric
3700 West
SamCompany
Houston Parkway,
A
Memeber
Suite
5077 of the ABB Group
PO
Box 2400
Houston,
TX 77402
Phone:
713-587-8055
Fort
Smith
AR 72901-2400
email: abblvps@us.abb.com
479-646-4711
www.baldor.com
2TDC190002 Effective 04/05/2010. Subject to change without notice.
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